Stable Single Longitudinal Mode Research Articles

Semiconductor internal-reflection-interference laser

A semiconductor interferometric laser with built-in index guiding for lateral mode stability is reported. Interference is caused by internal reflection from a small notch in the waveguide channel. Very stable single longitudinal mode and stable lateral mode were observed. The intereference also causes wavelength locking over the ranges of more than 7 °C within which the wavelength changes at a moderate rate of about 0.6 Å/°C.

Visible GaAlAs V-channeled substrate inner stripe laser with stabilized mode using p-GaAs substrate

A new visible laser, the V channeled substrate inner stripe laser, is developed. This laser can internally confine the current into the V-channel by using a thin n-GaAs layer grown on the p-GaAs substrate. cw threshold currents were 35–45 mA in the visible spectral range of 770–790 nm. And highly stable transverse and single longitudinal mode operation were observed because the built-in optical waveguide was formed within the V channel.

Room-temperature CW operation of 1.3 μm distributed-feedback GaInAsP/InP lasers

Distributed-feedback GaInAsP/InP lasers with a low threshold current emitting at 1.3 μm have been successfully fabricated. A minimum CW threshold current of 66 mA was obtained at room temperature. The temperature coefficient of lasing wavelength was 1 A/°C, which is about a fifth of that for Fabry-Perot lasers. A stable single longitudinal mode was obtained up to 52°C in a p-side-up configuration.

External cavity controlled single longitudinal mode laser transmitter module

A GaInAsP/InP laser transmitter module incorporating an external cavity is described. It is shown that the cavity produces stable tunable single longitudinal mode operation of the laser even under high speed modulation conditions.

Single mode nitrogen pumped dye laser

A N 2-laser pumped, tunable dye laser has been operated in a stable single longitudinal cavity mode without the use of etalons, polarized pump sources or intracavity polarising elements. The all-reflective cavity employs a grazing incidence beam expansion grating and a Littrow tuning grating. The time averaged linewidth of 0.02 cm -1 (630 MHz) for 5 × 10 -3 M R6G dye was observed to be the same as the single shot linewidth, with an efficiency of 0.5%. A dye concentration of 10 -2 M R6G increased the single mode linewidth to the value predicted by a single pass model of the cavity and increased the efficiency to 1.5%. A Littrow grating can be used to replace the feedback mirror and enhance the output signal to noise ratio.

Terraced Substrate GaAs-(GaAl) As Lasers

A new structure of stripe-geometry lasers is proposed where a double heterostructure is fabricated on a terraced substrate. The lasing mode is confined and stabilized in the narrow area between two adjacent bends of the active layer. No kinks have been observed in light output-current characteristcs. The terraced substrate laser exhibits a stable single longitudinal mode oscillation as well as a fundamental transverse mode oscillation. Beam divergences of far-field pattern in the direction parallel and perpendicular to the junction plane are 20° and 34°, respectively.